Thank you for getting back to us and I am sorry for the delay in my response. We are actually still researching the case - there was no intentional rolling back to an earlier version and your report is indeed alarming. We are still looking into what might have gone wrong on the server and it would help if you can remember whether there is a specific time frame in which changes were lost. For instance if you have lost all changes for the day or only the changes made an hour before the outage.
I am afraid that even when we do find the cause, we won't be able to restore your changes and I do want to apologize for this inconvenience. The In-Broswer client alerts you when changes to a file cannot be saved in which case you either have to save them locally and close the browser until the service is back up or leave the browser open until the service is back up. At the same time, we are doing our best to ensure there are no outages and to address any issue we detect as soon as possible. We are therefore investigating your report and I will keep you posted on the progress. Once we figure out what went wrong we will make sure not to let it happen in future.